SEVERITY OF SPROUTING AS A FACTOR INFLUENCING THE DISTRIBUTION OF AMYLASE LEVELS IN PILOT MILL STREAMS OF CANADIAN WHEATS

Abstract

Wheats from a wet harvest year, 1978, and a dry harvest year, 1979, were examined for levels of α-amylase in Grain Research Laboratory pilot mill streams. Specific α-amylase determinations were more discriminating than use of the amylograph in discerning differences in levels of enzyme. Wheats grown in 1978 had more enzyme present in the break flours and less in the middlings than wheats grown in 1979. On a per gram basis, a 1 CWRS wheat from 1978 and a 2 CWRS wheat from 1978 with comparable α-amylase activities had different distributions of enzyme in the mill streams. Thus the 1 CWRS 1978 contained a higher activity per gram in the 1st break, 6th middlings and bran flour but contained equal or less activity per gram in the other fractions. Model wheat systems containing 1.8% of 44-h germinated wheat and 0.3% of 96-h germinated wheat were examined for α-amylase levels per gram in pilot mill streams. It was found that the less severely sprouted system had less activity in the sizings and early middlings relative to the later middlings. These findings suggest that the observed differences in distribution of α-amylase in mill streams of wheats harvested in 1978 and 1979 can be explained by a greater severity of sprout damage in the 1978 crop year. The α-amylase versus mobility relationships for the different flour streams varied widely and was influenced by starch damage as well as other factors, β-amylase levels in the 1978 and 1979 pilot mill streams were found to have a different distribution than α-amylase.